Electrocardiography provides a set of standardized tests that are used for diagnosing abnormalities in the heart function of a patient. The standardized measurements record the potentials between various standard locations on the patient's body by placing electrodes in contact with the standard locations on the patient's body and recording potentials at the standard locations as a function of time. Most physicians are trained to read these graphs, which are often referred to as traces, as part of regular checkups or when a patient is exhibiting symptoms that may be caused by an underlying heart problem.
The standard twelve leads in an ECG test are divided into two groups, referred to as the standard leads and the precordial leads. The leads are generated by connecting ten electrodes to the patient's body and measuring the potentials between various ones of the leads or combinations of the leads as a function of time. In a clinical setting, the electrodes have adhesive pads for attaching the electrodes to the patient's body on the hands, feet, and six locations on the patient's chest, and the test is administered by a trained professional.
Unfortunately, the patient is often away from the clinical setting when a cardiovascular event is suspected. There are basically two solutions to this problem. The first involves connecting the electrodes to the appropriate locations on the patient's body adhesively and providing the patient with a portable unit that records the ECG traces. This type of solution generates traces that are essentially the same as those generated in the clinical setting; however, wearing the electrodes over a significant period of time presents numerous challenges if the patient also wishes to pursue a normal life.
The second solution involves providing the patient with a handheld unit that the patient uses to record various traces by holding the unit in the patient's hands and touching electrodes on the outside of the unit to various locations on the patient's body during the recording of the signals. Numerous devices have been proposed in which the handheld unit includes either three or four electrodes on the outer surface of the unit which the patient holds such that either one or both hands touch the electrodes while the patient places the remaining electrode at various points on the patient's body that are determined by the specific test or group of tests that are to recorded.
While these handheld devices allow the patient to perform one or more tests without having to affix electrodes adhesively to the patient's body, the resulting tests are not always a good approximation to the standard tests and present challenges when attempting to diagnose the patient based on these tests; however, even in the case of non-standard tests, these devices can be used to provide data on whether or not the patient's heart function has changed from the last tests performed with the handheld device.
All of these devices require the patient to maintain the electrical connection between the patient's skin and the electrodes on the handheld device for a period of seconds while the potentials on the electrodes are recorded. If the device loses contact between an electrode and the patient's skin, an abnormal recording will result. Since the patient is typically not a trained medical technician operating in a clinical setting, guaranteeing that the required pressure is applied between the patient's body and the electrodes in question presents significant challenges.